Valve for compound air-compressors.



PATENTED JAN. 23, 1906.

E. HILL. VALVE FOR COMPOUND AIR GOMPRESSOBS.

APPLIGATION FILED JAN. 24 1905.

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UNITED STATES PATENT OFFICE.

Specification of Letters Patent.

Patented Jan. 23, 1906.

Application filed January 24, 1905. Serial No. 242,498.

To all whom it may concern:

Be it known that I, EBENEZER HILL, a citizen of the United States,residing at Norwalk, in the county of Fairfield and State ofConnecticut, have invented a new and useful Valve for Compound Air-Compressors, of which the following is a specification.

The invention relates to a valve for the highpressure cylinder of acompound aircompres sor which is so devised that when air is drawn fromthe low-pressure cylinder or from between the cylinders the piston ofthe high-pressure cylinder will without interrupting its movement beautomatically rendered wholly or partly inefiective for a part of astroke, a whole stroke, or several strokes in succession orintermittently, depending upon the time the pressure between thecylinders is below normal.

The valve is applicable to the high-pressure cylinder of a compoundcompressor, also the highpressure cylinders of compressors having morethan two cylinders, and one or more of the valves may be arranged on theintake end of a single-acting cylinder or one or both ends of adouble-acting cylinder, according to the conditions.

This valve is so constructed that when the pressure in the interductdrops below normal it will be quickly thrust inward and surely held openas long as the pressure is reduced, so that for the time being thestroke or strokes of the high-pressure piston will sim ply cause air toflow back and forth through the port and not force air forward beyondthe high-pressure cylinder and cause a reduction of volume of air in theinterduct.

The object of the invention is to provide a valve of this nature whichwill act quickly and surely. This object is attained by arranging adifferential plunger which is moved in one direction by a spring and inthe other direction by the air-pressure in such manner that it willcause the valve to skip its regular function when the pressure in theinterduct is below normal, as more particularly hereinafter described.

Figure 1 of the accompanying drawings represents two cylinders of acompound aircompressor which has the high-pressure cylinder providedwith intake-valves that embody this invention. Fig. 2 shows a sectionalview, on larger scale, of one of these intake-valves, which is held openwhen the pressure between the cylinders drops below the construction.

desired degree as the result of the drawing off of air at low pressure.

Air is drawn into the low-pressure cylinder 1 through the intake 2 anddischarged into the interduct 3 by the reciprocations of thelow-pressure piston 4, the intake-valves 5 and the discharge-valves 6being of common The reciprocations of the piston 7 draw air into thehigh-pressure cylinder 8 from the interduct 3 and force it into thedischarge 9. The discharge-valves 10 of the high-pressure cylinder areof common construction; but the intake-valves 11 of this cylinder arewhat will be termed skipvalves, as they fail to operate or skip when thepressure in the interduct drops below normalas, for instance, when airis drawn through the outlet 12 for use at low pressure in order torender the high-pressure pistontemporarily ineiiective for drawing airout ofthe interduct. There may be one or more of these skip-valves ateither or both ends of the high-pressure cylinder, and they skip actionautomatically a sufficient number of strokes of the highpressure pistonto reserve air enough in the interduct to keep the low pres sureconstant. The skip-valve disk 13 opens inwardly from its seat 14 as thehigh-pres sure piston moves from it, so as to allow air to flow from theinterduct into the cylinder, and closes outwardly against its seat whenthe piston moves toward it, so that the air cannot pass back into theinterduct. The stem 15 of this disk is loosely supported by a hub thatforms a part of a cage 16, which is inserted in an opening in the end ofthe cylinder, so as to hold the valve-seat in position.

, Thrusting between the head at the outer end of the stem and the cageis a spring 17, which tends to draw the disk to its seat.

A cylindrical case 18 is screwed into an opening in the cylinder-headagainst a packing between the case and the cage, so as to hold thepacking, cage, and valve-seat securely in place. In the case is a sleeve19. At the inner end of the sleeve is a packing 20,

' and at the outer end of the sleeve is a packing 21. These packings andthe sleeve are held in place by a plug 22, which is screwed into. theouter end of the case. A hollow plunger 23-fits loosely in the sleeve.This plunger at its outer end has a flange 24, which is larger indiameter than the body of the plunger, andv at its inner end has aknife-edge or rib 25, which is smaller in diameter than the body of theplunger. The flange is adapted to seat tightly against the outer packingwhen the plunger is at the outer limit of its movement, and the edge isadapted to seat tightly against the inner packing when the plunger is atthe inner limit of its movement. In the plunger and plug is a rod 26,and thrusting between the head of this rod and the plug is a spring 27.This spring and rod tend to force the plunger inwardly toward the end ofthe disk-stem. Passages 28- are made through the cage, so that theintake-passage 29, which communicates in the usual way with theinterduct, will communicate with the chamber 30 in the case and theplunger be subjected to the intake-pressure. As the plunger does not fitthe sleeve perfectly tight, air can leak outwardly between the plungerand the sleeve and exert its force against the inner face of the flangeon the end of the plunger, which flange loosely fits the enlarged partof the sleeve, so that air can escape around it into the plug andthrough the opening 31 in the end of the plug to the atmosphere. Whenthe pressure in the intake-passage, which is the same as in theinterduct between the two cylinders, is normal, that pressure is exertedagainst the inner end of the plunger and the plunger-flange and forcesthe plunger back against the thrust of the spring, so that theflangeseats tightly against the outer packing. With the plunger in thisposition the spring inside is under its greatest tension, and as theflange seats tightly against the outer packing air cannot escape aroundthe flange and through the plug to the atmosphere. When the pressure inthe intake-passage drops below normal as, for instance, when air isbeing drawn at low pressure from the interductthe pressure on the innerend of the plunger and the plunger-flange becomes reduced to such anextent that the spring will drive the plunger inwardly and cause it toforce the valve-disk away from its seat. The plunger remains in thispositon, holding the valve open, as long as the pressure in theintake-passage is below normal. As soon as the plunger starts inwardlyand the flange moves away from the outer seat the pressure becomes equalagainst the opposite sides of the flange, for the reason that the edgeof the flange does not fit the wall of the sleeve closely. As the resultof this the pressure opposing the thrust of the spring, which naturallybecomes weaker as it expands, is only that on an area having thediameter of the body of the plunger. After the plunger has moved way inand the inner edge is seated against the inner packing the pressurewhich is exerted against the thrust of the spring is only that on anarea which has the same diameter as the inner seating edge, so that whenthe spring has expanded to its full extent and is weakest it is.

required to resist a much less pressure than it did when the plunger wasat the outer limit of its movement. When the pressure in theintake-passage rises to normal, that pressure is first exerted againstan area having the diameter of the" seating edge and then when that edgehas moved away from its seat against an area having the diameter of thebody of the plunger and finally when the plunger is wayout and theflange is seated against an area having the diameter of the flange. Aslong as a skip-valve is held open by the plunger the reciprocations ofthe piston in the highpressure cylinder merely cause air to flow in andout the port, and thus the piston will not perform its usual function.The reduction of pressure in the interduct may be such as to cause thevalve to skip that is, to remain open-for only an instant or for sometime, and the piston may thus be rendered ineffective for a part of astroke, a whole stroke, or several strokes in succession, orintermittently, and when thus rendered ineffective the piston does notdraw air from the interduct and force it forward, so as to reduce thevolume of air between the cylinders, and thus cause a variation of thepressure of the air which is being drawn off from between the cylindersfor low-pressure use. As a result of the differential areas of the seatsat the ends the plunger is held back when the spring is the stiffest bypressure on a large area, and when .the spring is weakest it only has toovercome a pressure on a small area. This also causes the plunger to actquickly, for when moving inwardly the areas of pressure diminish andwhen moving outwardly the areas of pressure increase.

The invention claimed is 1. A valve for the intake-passage of anaircompressor having a valve-disk adapted to open and close the passage,a plunger movable toward and from the disk, said plunger having asurface at its inner end that is exposed to the air-pressure in theintake-passage when the plunger is at its inner limit, and a largersurface back from its inner end that is exposed 'to the air-pressure inthe intake passage when the plunger is moved from its inner limit,whereby the pressure against the smaller surface will tend to move theplunger away from the disk and pressure against the larger surface willtend to hold the plunger away from the disk, and a spring arranged toforce the plunger against the airpressure when the pressure drops belownormal and cause the plunger to interfere with the ordinary action ofthedisk, substantially as specified.

2. A valve for an air-compressor having an inwardly-opening valve-disk,a spring tending to draw the disk to its seat, a plunger movable towardand from the disk, said plunger having surfaces with areas of diflerentextent arranged to be subject to the airpressure on the intake side ofthe disk, the

smaller surface only being subject to the airpressure when the plungeris at its inner limit and both the smaller and larger surfaces beingsubject to the air-pressure when the plunger is back from its innerlimit, and a spring arranged to force the plunger against theairpressure when the pressure drops below normal and cause the plungerto interfere with the ordinary action of the disk, substantially asspecified.

3. A valve for an air-compressor having a valve disk, a plunger movabletoward and from the disk and having surfaces with areas of differentextent arranged to be subject to the air-pressure on the intake side ofthe disk, a seat at the inner limit of movement of the plunger againstwhich the inner end of the plunger seats and leaves only the smallersurfaces exposed to the air-pressure when the plunger is at its innerlimit, a seat at the outer limit of movement of the plunger againstwhich the outer end of the plunger seats so that the air-pressure willbe exerted against the smaller and the larger surfaces of the plungerwhen the plunger is at its outer limit, and a spring arranged to forcethe plunger against the air-pressure when the pressure drops belownormal and cause the plunger to interfere with the ordinary action ofthe disk, substantially as specified.

4. A valve for an air-compressor having a valve-disk, a plunger movabletoward and from the disk, said plunger having a seating edge at itsinner end that is less in diameter than the diameter of the body of theplunger, and a seating-flange at its outer end that is greater indiameter than the diameter of the body of the plunger, a seat againstwhich the inner edge seats when the plunger is at its inner limit, aseat against which the outer flange seats when the plunger is at itsouter limit, and a spring arranged to thrust the plunger against theair-pressure when the pressure drops below normal and cause the plungerto interfere with the ordinary action of the disk, substantially asspecified.

' 5. A valve for an air-compressor havin a valve-disk, a spring tendingto draw the dlsk to its seat, a case, a sleeve in the case, a seat ateach end of the sleeve, a plunger movable in the sleeve toward and fromthe seats and subject to the air-pressure on the intake side of thedisk, said plunger having a seating edge at its inner end and a largerseatingflange at its outer end, and a spring tending to thrust theplunger against the air-pressure toward the disk and cause aninterference with the ordinary action'of the disk, substantially asspecified.

6. A valve for an air-compressor having a valve-disk, a spring tendingto draw the disk to its seat, a case, a sleeve in the case, a packing ateach end of the sleeve, a nut holding the sleeve and packings inposition, a plunger movable in the sleeve toward and from the packings,said plunger being subject to the air-pressure on the intake side of thedisk and having a reduced seating edge at its inner end adapted to seatagainst the inner packing and an enlarged seating-flange at its outerend adapted to seat against the outer packing, and a spring tending tothrust the plunger against the air-pressure toward the disk,substantially as specified.

EBENEZER HILL. Witnesses:

E. HILL, Jr. HOWARD H. MOSSMAN.

